


tadashi's guide to raising a genius

by arbhorwitch



Category: Big Hero 6 (2014)
Genre: #brosbeingbros, Angst and Humor, Brother Complex, Fluff, Gen, Humor, brotherly shenanigans, nerd alert tbh
Language: English
Status: Completed
Published: 2015-02-14
Updated: 2015-02-20
Packaged: 2018-03-12 07:21:58
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 11,877
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/3348527
Author URL: https://archiveofourown.org/users/arbhorwitch/pseuds/arbhorwitch
Summary: <blockquote class="userstuff">
              <p>It's not as easy as it sounds. </p><p>- </p><p>#4: in which hiro is sick and life generally sucks for a day.</p>
            </blockquote>





	1. #293 and the coffee ban (stop letting hiro buy energy drinks)

**Author's Note:**

> this is just gonna be a bunch of pre-bh6 one shots with potential post-bh6 au fics because tadashi is Absolutely Alive in this universe (can u taste my denial?????) honestly i just have way too many feelings about this movie and it's manifested into a very strong desire to let hiro and tadashi be happy w/ their aunt and fronds and everything is fINE IT'S ALL FINE 
> 
> （　´∀｀）☆
> 
> (no incest whatsoever so if that's what ur into it's not gonna be here soz)

**Rule #293:**

**No staying awake for more than 40 hours unless supervised.** _i get the garage!!!_ **Aunt Cass is on emergency standby.**

*

Hour twenty-nine is fine, Hiro thinks, even though his hands shake every time he so much as grazes his keyboard, but he's  _totally fine._ By the time hour thirty-nine hits, he’s had six knock-off energy drinks in the last hour and his heart feels as if it’s going to pound out of his chest and become one with his screen. He can’t say he’d be surprised.

He’s not even sure what he’s working on anymore, honestly. It had gone from the schematics for the upgrades on the micro-bot-bot, to new plans to tweak the ceiling fan A.I. that Tadashi had banned him from, to wondering if putting thrusters on a cat was actually a viable idea and not sure to end in massive burns and a medical bill for everyone involved. His computer looks strange and awfully blurry, the tablet pen in his hand beginning to slip out of his grip, but Tadashi isn’t due home for another three hours and Aunt Cass had gone to bed after she made sure Hiro was asleep. He’s become a master of lies; the thought makes him frown and poke uselessly at his monitor. It bleeps gloomily, probably sensing his discomfort.

Hiro takes another swig of his drink and is abruptly reminded of the time Tadashi poured an entire can of Red Bull into his morning coffee, drinking it in one go without any sign of having done so. They don’t talk about it.

“I could do it,” he says out loud, shushing himself when he realizes Aunt Cass can probably hear him in her sleep. Mochi meows somewhere to his left. In a quieter voice, he says, “I could totally do it.”

Unsurprisingly, it doesn’t go quite as planned.  

*

If they ask him on his deathbed what he was thinking, Hiro will say that it was an experiment, an attempt to unlock the doors to forbidden science, a necessary sacrifice.

Hiro doesn’t even _like_ coffee, thinks it tastes like bitter, stale beans and something awful, but he pours half into a glass and watches it with wary eyes anyway. Logic dictates that if it’s cold, it probably tastes better—this directly applies to pizza. He’s definitely going to ask his aunt for pizza tomorrow night. Extra cheese.

The energy drink is next and it fizzes awkwardly in the brown goop, a weird concoction of caffeine within caffeine. It smells terrible and for the first time since coming up with this amazing plan, Hiro takes a moment to regret his life decisions.

And drinks it anyway.

The microwave reads 4:56, Mochi is meowing concernedly at his feet, Aunt Cass forgot to turn the tap off all the way and it’s doing that leaky thing Tadashi keeps meaning to fix, and the drink he just tasted is like injecting coffee straight into his brain and it’s _horrible_. He spits out the first mouthful, forces himself to swallow the rest, and promptly leans against the counter and slides to his butt in grim defeat. The kitchen floor is cold.

“Conclusion: terrible and semi-good do not mix,” Hiro states, holding up a finger to further his point. Mochi paws his way into his lap and looks up with a very cat-esque glare. “My hypothesis failed me. Science isn’t worth it.”

“Science is always worth it,” a voice says, seemingly from nowhere like a ghost of caffeine past, and Hiro smacks his head off the cupboard door behind him and swears under his breath. A dollar into the jar, then. “Hiro, why are you still awake?”

He leans slightly to the side, just enough to see past the edge of the bar directly across from him, and finds Tadashi staring at him with an eyebrow raised and an extremely concerned look on his face.

“Science,” he states dully, blinking slowly. If he dies on their kitchen floor, Aunt Cass will _never forgive him_. “Mochi insisted.”

“Mochi is a cat,” Tadashi points out, dropping his bag on the floor and easing his way towards Hiro. Very slowly, Hiro notes. His head really, _really_ hurts. “When was the last time you slept?”

Asking what day it is will probably lead to questions Hiro doesn’t want to answer, so he grins and says, “The last time I was in bed.” It’s not technically a lie, actually quite close to the truth, and Hiro gives his brother an extra point for managing to stay patient.

“Hiro,” he begins, but aforementioned child holds up his other finger before he can continue.

“ _Science_ ,” he says, pointing to the cat in his lap. “Coffee and energy drinks are gross.”

“You didn’t.”

“I totally did.”

He should probably tell Tadashi that his computer screen is starting to become sentient and that he can’t sleep because there are at _least_ forty-eight reasons why sleeping is more of a nuisance than a necessity, he just has to find them, but he opts for scratching Mochi behind the ears instead. 

“Hiro.” Tadashi sounds serious and Hiro perks up, drags his fingers through soft fur. “How many hours?”

“You’ll get mad,” is his argument, and Tadashi visibly swallows a sigh. “Good morning, though. I think you’re early.”

“Time, Hiro.”

“Hm.” He looks at the microwave, tilting his head to do so, and narrows his eyes and begs them to focus. He makes out a five, a zero, and either an eight or a six. “Sometime after five.”

He’s pushing _so many buttons_. It’s a miracle Tadashi hasn’t woken up their aunt for back-up.

“I’ll make you a deal,” he says and _that_ gets Hiro’s attention, because deals usually involve money and money means getting the finishing part for his robot he can’t afford yet. Tadashi bows down to his level and looks him straight in the eye when he says, “If you go to bed and sleep, I’ll pretend I never saw this _and_ spare you a lecture on caffeine addictions.”

Unacceptable. He didn’t blow a week’s worth of energy drinks in two days for _this_.

“Monetary value or nothing.”

“I thought we passed bribing when you turned eleven.”

“Blame the economy, bro.”

Tadashi sighs again, scrubs his face with his hand, and sticks out his lower lip. Hiro refuses to break.

“I’ve named my terms,” he says firmly, Mochi adding a strange _mrrow_ to punctuate this. “A boy’s gotta eat.”

“You ate an entire cheesecake last Wednesday. I’m pretty sure Aunt Cass is trying to fatten you up.”

“Yeah,” Hiro agrees, reminiscing happily as Mochi licks his hand. “But that cake was awesome. Also irrelevant because that was Wednesday and this is Saturday.”

Wrong thing to say apparently, because Tadashi is suddenly leaning forward and hooking his hands under Hiro’s arms, dislodging the poor cat from his lap in the process. Somewhere between his descent from the floor to his brother’s shoulder, he hears, “It’s _Monday_ , bonehead, you have school in three hours, have you seriously been up all weekend?” and isn’t that grand, he is _so busted._ The rational part of his brain is warning him that he left his bot schematics open on his computer and yeah, Tadashi will definitely see, that’s an issue and a half right there, and—

“Hey,” Hiro mutters, slapping weakly at his brother’s back. Despite his precarious position, Tadashi is doing a fairly good job at not jostling him as he goes up the stairs, merely offering a grunt of fond annoyance at the resistance. “Hey, _hey_ , I have my algebra test today. I should tattoo the quadratic formula on my arm. Is that cheating? That would suck.”

“You memorized that formula when you were four,” Tadashi reminds him. Hiro laughs, kicks at his brother’s midsection. “Cut it out, Hiro. I’m surprised you haven’t gone into cardiac arrest.”

“I don’t want to go to school,” he admits, giving up on attempting to escape. One day, _one day_ he’ll surpass Tadashi’s strength. “Can’t I just graduate now and get it over with? My life awaits.”

Silence follows awkwardly; by the time they finally reach their bedroom, Hiro has the distinct feeling of being utterly void of all thought processes and his head is threatening to implode on itself. It’s a small relief when Tadashi grabs the blanket bunched at the edge of his bed and drags it over Hiro; he can _feel_ the oncoming lecture.  

So it’s a bit of a surprise when Tadashi takes a seat beside him and asks, “Are they still bothering you?” rather than listing off the exact reasons why sleep deprivation and caffeine overdoses are both Very Dangerous Things.

“Nope,” is his immediate reply, fiddling with a loose thread at the edge of his too-big nightshirt. It’s five in the morning and Hiro would rather do something with his hands than talk about whether or not the assholes in his class are any less asshole-ish; they’re not, and he may be riding on some sort of caffeine high, but he’s not about to admit that to his brother. Again.

“You can tell me, you know.”

“I know.”

“So are you going to tell me?”

“Nope.”

“Hiro.”

“I’m thirsty,” he declares, making to get up but stopped by a hand on his chest. He offers a half-hearted glare in return of Tadashi’s “I’m disappointed but I know you mean well” look.

“No more sugar.” He stands up, flicking off the lamp by Hiro’s bed and heading towards the bathroom. “Water only. Do you want me to leave out some Tylenol for the morning?”

“I’m not _drunk_ ,” Hiro mumbles, rolling his eyes; Tadashi snorts and hits the light switch by the bathroom, effectively bathing them in near-darkness. Through the window above his bed, Hiro can see the sun trying to peek through the houses across the street, a murky half-glow to the low hanging clouds that reminds him of the underground. He takes the few precious seconds of unwatched freedom to snatch his wireless mouse off his desk and save his programs, shutting them down quickly before sending his computer off to cyber-sleep.

If Tadashi notices anything by the time he comes out, he doesn’t say, simply handing Hiro a paper cup filled halfway with warm water and setting a pill on his nightstand. “Just in case,” he explains at Hiro’s insulted glare. “You’re gonna feel this in the morning, trust me.”

Hiro shrugs, downing the water in one go before asking, “How was the convention?”

“It was pretty awesome.” Tadashi grins, taking the empty cup from Hiro’s hand and tossing it in the bin by his bed. “Got you some neat stuff, but that can wait ‘til tomorrow.”

“Nerd,” Hiro mutters, feigning exhaustion and flopping back on his pillow. Tadashi laughs at him and tucks him back in before disappearing into his own side of their bedroom, kicking a few crumpled notebook pages as he goes.

“Sleep, kiddo. I’ll see if I can talk Aunt Cass into letting you stay home.”

“But _formulas_ , Tadashi. _Formulas._ ”

“Uh-huh.” Hiro watches him plug in his phone on his desk and fall into his own bed. “Thought you guys would be on trig by now.”

“We should be,” Hiro snaps, waving his hands above his head in protest. Maybe if he traces enough triangles in the air, they’ll magically appear. “But everyone in my class is dumb. Mr. ‘Stop stealing the chalk Hiro’ is dumb. We’ve been on algebra for _three weeks_. I thought this was supposed to be advanced stuff.”

Tadashi makes an indistinct noise, propping his chin on his hand to stare at his brother. “What about physics?”

“Physics? Is that a myth?” Hiro snorts, his hands hitting his mattress. He vaguely realizes that Tadashi is doing this purposely, letting the caffeine work its way out of Hiro’s system so he doesn’t have the energy to sneak away. Clever: Hiro can’t pass up an opportunity to complain about his classes. “Chapter four, Tadashi. Four. That’s, what, a quarter of the lesson plan? We’ve been learning the same three equations since forever.”

“Mhm.” Tadashi nods, mirroring Hiro’s expression of frustration. “Should I even ask about computer science?”

“How do these people even _function_ , oh my god,” he claims, slapping his face in horror. Hiro gives serious points to his brother for holding back his laughter. “Half of my class can’t _open_ Excel, let alone _use_ it.”

They sink into a comfortable silence, a faint humming coming from Tadashi’s laptop, his cellphone flashing with new messages and a missed call, his brother’s steady breathing in the quiet that’s been absent the last few days. He’s hyperaware of his fingers jittering against his forehead, the way the fleece of his blanket scratches painlessly on the skin of his stomach. Post-manic exhaustion is familiar and awful, curving deep into the contours of his muscles and joints, an ache that won’t settle with two hours of measly sleep.

“Hey genius,” Tadashi calls, startling Hiro out of his stupor. Maybe if he pretends he can breathe, his body will get the message. “If you’re up for it, we can go see a movie tomorrow night. The new one with the kaijus and ‘super sick animation’, if Fred’s word can be trusted.”

“What—really?”

“Really. Unlike _somebody_ , I know how to save my money.”

He takes the jab for what it is and grins, cocooning himself in his sheets and rolling onto his side to better face his brother.

“New rule, though,” Tadashi adds, reaching over to rummage in his desk drawer. Hiro’s suspicions rise until he sees the familiar red journal packed with old, scribbled napkins and worn sticky notes, a collection of their combined handwriting. “293: no staying up for more than thirty hours.”

“But what if we have a project idea? Thirty is a pretty limited number.”

Tadashi taps his chin with the pen, smudging ink on his face, and says, “Okay, forty hours on Fridays, Saturdays, and holidays. Thirty-five on school nights. No more than forty unless I’m supervising or Aunt Cass is on standby for emergencies.”

“And if you’re on a nerd trip?”

“Thirty-three and Aunt Cass monitors your sugar intake.”

“ _What_ —“

“If the rule is broken, standard punishment applies.”

“Thirty-five _and_ I get access to your junk box in the garage.”

“You drive a hard bargain, but deal.” Tadashi chuckles, adding the necessary clauses onto the half-filled page with his messy scrawl. Hiro climbs out of bed and wanders over when he’s done, stealing the pen from between Tadashi’s fingers along with the journal, a determined frown gracing his lips as he signs his name.

“Done,” he whispers, snapping the book shut and repositioning himself so the back of his head is draped over Tadashi’s stomach. Tadashi, unconcerned, flicks Hiro’s nose and waits for the oncoming storm.

It never comes; Hiro has twenty-one things he wants to say to Tadashi about school and robots and coding, but it’s been three days since he’s seen his brother and actually slept and he doesn’t really care if he’s going to wake up with a sore back and a headache.

He drifts to the sound of birds waking up as the sun peeks over the horizon, the strange ambience of early commuters and bikers skidding along the sidewalk, Aunt Cass beginning to stir to prepare for the morning rush.

“Nerd,” Tadashi murmurs, and it’s the last thing Hiro remembers.


	2. valentine's day is for nerds

**Notes for the Chapter:**

> technically it's still valentine's day here so hopefully i didn't miss it by too much (thanks work) 
> 
> i love the concept of valentine's day even tho i hate this holiday idk. i always spend it with my family n i firmly believe these three were total saps and thus this was born 
> 
> probably considered an au since tadashi is 100% alive and it's assumed he survived the fire and they all get to study together (is that denial i taste???)
> 
> for cam bc i love her lots and she puts up with my never ending stream of bh6 skype shenanigans ♥

“But you said you’d be here for Valentine’s!”

“I’ll be home before you know it.”

“But you _promised_.” Hiro folds his arms over his chest and stomps his foot just a little, not quite a pout but not exactly pleased, either. Tadashi looks properly chagrined and apologetic, but it doesn’t make up for the fact that his brother is breaking a four year tradition for something as dumb as school projects and _friends_. “’Sides, you don’t even like them!”

“Hiro.” Tadashi sighs, brushing his bangs out of his eyes. Hiro briefly thinks about giving him a haircut while he’s asleep as revenge. “Just because I don’t like them doesn’t mean I’m gonna make them do all the work.”

“You could do all the work,” Hiro argues, kicking his feet against the legs of the kitchen chair. He’s not tall enough to reach the floor yet, barely reaching the four foot mark, but he’s getting there. “I could do all the work.”

There’s a burst of startled laughter and a hand gently patting his hair, but Hiro shoos it away and says, “ _Seriously_ , I could do it! What is it?”

“Environmental science,” Tadashi replies, giving one last pat before heading towards his shoes downstairs. Hiro slides off the chair and grabs a handful of chocolate hearts, following Tadashi with a frown. “And I don’t think my teacher would appreciate my homework being done by my seven-year-old brother.”

“He’ll just be mad I’m smarter,” Hiro mutters, popping another piece of candy into his mouth. Tadashi shakes his head, tying up his sneakers with a grin. “Why’d you take that stupid class anyway?”

“It’s an elective,” he explains, straightening up to slip on his coat. “When you’re in high school, you’ll get to pick electives too.”

Hiro snorts, an awkward sound that’s muffled by the chocolate he’s still trying to chew, and says, “Mmph-ss.”

“I don’t speak candy.”

“Mnphh!”

“Language, Hiro.”

“ _Mmphss,_ ” he exclaims, throwing his hands up in the air in defeat. The chocolate is sticking to the roof of his mouth and between his teeth but he finally manages to swallow it, earning an exasperated smile from his brother. “High school is dumb!”

“It can be fun,” Tadashi assures, pocketing one of the hearts Hiro offers him. He double-checks the contents of his backpack to ensure he has the necessary notes and materials before bending down to Hiro’s level, holding out a hand. “I promise I’ll be home by seven, okay? And then you can show me what you’ve been working on for Aunt Cass.”

This time Hiro does pout, a kneejerk reaction to the prospect of being alone for the day, but slaps Tadashi’s hand anyway and asks, “What am I gonna do?”

“I think Aunt Cass could use some help downstairs.” He curls his hand into a fist and Hiro mirrors him. “You can practice your listening skills.”

“Ha-ha,” he mutters, bumping his tiny hand into Tadashi’s and letting it explode with a quiet _whoosh_. “She won’t let me near hot coffee.”

“That’s because you almost burned your hand off trying to remodel the machine,” Tadashi reminds him, pecking Hiro on the forehead and reaching for the door. “Be good, I got a surprise for you later.”

Hiro watches him, a quiet _bye, Tadashi_ on his lips, until he’s out the door and into the midday sun.  

And then he gets to work.

*

“Stupid paper cut,” he mutters, shaking the card and letting the screws fall out. He takes a pair of tweezers and pulls out the voice chip, tossing it on his desk with a concentrated frown and blood seeping from the wound on his thumb. “Band-aid, band-aid… Oh yeah.”

He sucks on his finger to ease the stinging and pushes away from his desk, glancing over at Tadashi’s side of the room; it’s neater than his, most things picked up and straightened, but Hiro’s done this enough times to remember exactly where he needs to go. Second drawer of Tadashi’s nightstand underneath their journal is the first aid kit, and he rummages through it until he comes up with a small bandage with cats on it that won’t get in his way. He contemplates the anti-bacterial spray but decides against it, remembering the last time he used it on a scrape and the burn that had itched his skin for _hours_ ; he doesn’t have time for that today.

Booting up Tadashi’s computer, he starts phase two.

*

“Hiro! There’s a plate of extra éclairs with your name on it,” Aunt Cass calls a few hours later, startling Hiro out of his intent concentration on holiday cards, the edge of the chip slicing through his middle finger. He breathes out and slams his head on the desk a few times, various codes flashing before his eyes; this is how he’s going to die, he just _knows_ it. “C’mon!”

“Sec,” he yells back, saving his progress and reaching for _another_ band-aid, haphazardly sticking it around his finger.

At least this one has dinosaurs on it.

*

“Nnph,” he articulates, sinking his teeth into another éclair. Aunt Cass hides her mouth behind her hand and tries not to laugh. “Nphhmmn?”

“Honey, I’m not Tadashi,” she says, taking a bite of her own dessert. Hiro continues to chew, pointing to the cream-filled pastry in his hand. “English or German only, kiddo.”  

“Mmmn,” he explains slowly. Aunt Cass nods and encourages him to continue. “Phhn, mhm.”

“Well,” she says with a smile, reaching forward with a napkin to wipe away the excess crumbs around Hiro’s mouth, “I’m glad you like them.”

She has her hair pinned back today, a bow made of hearts stuck behind her ear, and it reminds Hiro that neither of his gifts are done yet, sending a shock of anxiety through his gut. He darts off the chair with a, “Thanks Aunt Cass, I’ll be right back!” and promptly disappears back up the stairs.

“Don’t burn anything down!” she calls after him happily and Hiro grins, shutting his door behind him with new resolve.

*

Recording is definitely the best part.

*

Seven o’clock hits him quick and fast, the sound of the front door opening and closing drifting into the space he’s created for himself. It smells like spice and grease downstairs, the deep fryer crackling in the kitchen, and Hiro panics, taking both of his finished projects and hiding them under his pillow. Before Tadashi can see, Hiro shuts down his brother’s computer, tries to reorganize the messy desk so it’s less of a violated disaster zone, and then hightails it to his own computer and opens up the first thing he sees.

It turns out to be the math game Aunt Cass had picked up for him when he was four, and Tadashi laughs the second he walks into their bedroom.

“I haven’t seen you play that in years,” is the first thing he says, Mochi trailing in behind him. He belatedly realizes that keeping the door shut meant also keeping Mochi out, but all is forgiven when Mochi paws his way onto Hiro’s bed for an evening nap.

“I was bored,” Hiro deadpans after a moment, closing the game and stretching. “Someone ditched me for _school_.”

“Aw, don’t be like that,” Tadashi says, tossing a wrapped package that Hiro barely catches. “That’s what you’ve been after, right?”

Hiro unties the ribbon and peels back the paper, only to come face-to-face with the one part he’s been missing to finish his latest robot, shiny and sleek and brand new. His eyes widen and he tries to ask how Tadashi had even managed to get a hold of this, but he’s crushed by his brother’s arms before he has a chance.

“’Dashi, this is _perfect_ ,” Hiro cries, hugging back and smiling brightly.

“Rule fifty-three,” Tadashi reminds him, letting go to shrug out of his coat and into a sweater. “If it’s something one of us _really_ wants, any holiday counts.”

“Making up holidays is also allowed,” Hiro continues, letting his fingers graze over the metallic surface shining up at him. “Side-note: if it’s over ten dollars, no price is to be mentioned.”

“Mhm.” Tadashi ruffles his hair and sits on Hiro’s bed beside Mochi, absently petting him with a small smile. Mochi, content, merely purrs and licks at his hand. “So, you gonna tell me what you did all day?”

Hiro’s about to make up an incredible tale of adventure and sacrifice, but Aunt Cass beats him to it when she knocks on their door and says, “Boys, dinner is ready! Special Valentine’s treat.”

*

“Extra spicy,” Tadashi breathes, downing half his glass of milk in one go. Hiro laughs at his expense and takes another bite of his wing, the heat making his eyes water and his tongue burn pleasantly. “Hiro isn’t human.”

“Of course he is,” Aunt Cass assures, nudging Hiro’s glass closer. She’s learned to watch how many wings he can stuff into his mouth before burning from the inside out, and she’s learned when to cut him off, one of the few things Tadashi hasn’t managed. “How did the project go, sweetie?”

Hiro takes a sip while they’re both distracted, immediately grabbing another piece of chicken.

“It went fine,” he replies, wiping his fingers with a napkin and placing a clean one next to Hiro’s plate. Hiro glances at it, decides it’s not important, and continues eating. “We banned Marly from touching any sharp objects. He almost cut his finger off with a pair of scissors.”

“I _told_ you should have let me do it,” Hiro claims, waving a bone at Tadashi who looks torn between laughing and exasperation. “I’ve never cut myself with scissors!”

“What are the new band-aids from?”

“That’s a surprise,” he mutters, shrinking back into his seat and stealing one of Tadashi’s fries. All he gets for his effort is a chuckle and another napkin thrown his way.

“So,” Aunt Cass starts, pushing her plate away and casting a strange look in Hiro’s direction. Hiro swallows carefully, eyes darting between his aunt and Tadashi, “Hiro’s been locked away in his room all day and I think we’re both dying to know why.”

She’s giving him an opening like she does every year, an encouragement to show off, and Hiro excuses himself to flee upstairs and grab the cards from under his pillow; they’re not spectacular and there was a plethora of errors with his original coding, but the recording came through and there’s no blood on the finished products. When he comes back downstairs, Mochi on his heels and keeping him from bolting, Tadashi and Aunt Cass are already in the living room with the television playing on a random music station. It’s upbeat, turned down low, and the bassline eases some of the anxiety trying to bloom in his chest; he steps in front with his hands behind his back and the cards clutched between his fingers.

“Okay,” he begins, rocking back on his heels and finding interest in the ceiling. There are a thousand and three bumps from corner to corner. “First is Aunt Cass.”

He hands her the white and pink folded card, a crane with intricate designs on the paper that he had bought specifically for this occasion; there’s no written message on the inside, but he knows Aunt Cass has always been fond of origami and won’t mind putting it back together. He explains, “There’s a chip on the inside so watch out for that, but if you open it all the way…”

She does and the room is filled with a lullaby that Hiro doesn’t quite remember but Tadashi catches onto immediately.

“Oh my,” Aunt Cass breathes, and he _really_ hopes she doesn’t cry. He’s not prepared for that. “Hiro, how did you—this song…”

“I remembered the main parts for it,” he says quietly, fiddling with the other card behind his back. “It’s not the exact same, obviously, I had to do some rendering, but Tadashi had something like it on his computer and I went from there.”

Tadashi cocks an eyebrow, unsure whether or not to be impressed when he asks, “How did you get on my computer?”

“Your password is obvious, nerd,” Hiro mutters with a shrug. “Took a single try.”

Aunt Cass clears her throat and ushers him over, embracing him tightly and warmly. “It’s perfect, honey,” she says sincerely, kissing his cheek. “That song used to be your mother’s favourite.”

There’s the familiar pang of sadness whenever his parents are mentioned, a grief more reserved for his brother’s loss than his own—he barely knew his parents, can only remember the nursery and his mom’s favourite necklace. He remembers the separation anxiety. He doesn’t remember _them_ specifically, not the same way Tadashi does.

“This one’s for you,” Hiro says suddenly, pushing past the inexplicable pressure building behind his eyes. He hands Tadashi a normal sized card with hand-drawn, familiar symbols: their rule journal, a message in binary that reads _you’re a huge nerd_ that Tadashi understands immediately. Inside is a laminated family picture that they had taken in front of the bridge downtown, the most recent one Hiro has, and it’s surrounded by random pictures that Aunt Cass had given him access to when he had explained what he needed them for. In half of them, Tadashi is caught unawares, usually tending to Mochi, dealing with Hiro, or helping Aunt Cass in the café (Hiro had taken those ones).

“It’s perfect,” Tadashi murmurs, his fingers grazing over the photos. “Seriously, Hiro. Thank you.”

“Don’t get all sentimental on me!” he exclaims, holding onto the shred of his reputation he has left. It’s hard having your closest friend be your older brother. “…But I’m glad you like it.”

Tadashi snorts and pulls him into a hug, Aunt Cass gripping both of them and sharing in the slightly awkward, completely dysfunctional family hug.

“Oh!” Hiro pulls away enough to point at a small button on the corner of the card. “I recorded a message, but don’t listen to it ‘til I’m asleep, okay?”

“Okay.”

They end up watching Godzilla until three in the morning with Aunt Cass, a holiday well spent.

*

Years later, when Hiro is fourteen and trying to build his robotics assignment without pulling out every single strand of his hair, he finds a card buried at the bottom of Tadashi’s top desk drawer.

He’s not supposed to snoop and if Gogo catches him, she’ll have no qualms about telling Tadashi, but he can’t help it; he pulls it out and is promptly reminded of all those years ago, the amateur remodelling of a premade chip and the sketchy code that he still has saved somewhere on Tadashi’s hard drive.

“He actually kept it,” he mutters, which automatically catches Honey’s attention and suddenly she’s looking over his shoulder with Wasabi and Fred on her heels.

“Oh Hiro, that’s adorable,” she coos, rubbing his shoulder encouragingly. He’s not embarrassed, he’ll swear by that, but his cheeks flush regardless.

“I made this when I was _eight_ ,” he says defensively, lower lip in an unnoticeable pout.

“Seven, actually,” someone says behind them, and the three teens turn around to see Tadashi leaning against the door with Gogo beside him. “And it was pretty impressive work.”

“Totally amateur,” Hiro argues, holding up the card by the corner and raising an eyebrow. “Compared to Baymax’s code? This is awful.”

“Baymax took me months to do,” he points out, walking towards Hiro to grab the card. “If I’m not mistaken, you made this _and_ the recording in less than a day.”

“Oh my god the _recording_.”

“Recording?” Honey asks, poking at the contraption in Tadashi’s grasp. “Can we hear it?”

“No no _no_ —“

“I don’t see why not.” Tadashi grins, the traitor, and presses the tiny button before Hiro can react. His voice fills the room, high-pitched with a slight lisp, and Hiro shouts a cry of distress and proceeds to bury his face in Baymax’s stomach.

“There, there,” the robot says after the card falls silent and the others try to smother him with laughter and too-tight squeezes; his effort to hide his mortification in Baymax falls short when it turns into a massive, perfume-and-cologne hug. “I believe it is the thought that counts.”

He’ll never, _ever_ live this down.

*

_Hey Tadashi, happy Valentine ’s Day I guess. I think it’s kind of a dumb holiday because we basically celebrate it every day but whatever. I just wanted you to know that this gift is the BEST EVER and you should be very impressed with your little brother’s work. Even though you always are. Anyway, you’re a dork and I love you and I wanted to thank you for being my friend because I know how hard that can be sometimes? Yeah. Also, you should probably rename your private folder to something less obvious you giant anime nerd weaboo. Hiro out!_

**Notes for the Chapter:**

> my headcanon is that cass can speak english and german but limited japanese, whereas both hiro and tadashi speak fluent english and japanese, tho tadashi knows more simply bc he had more of a chance to learn it 
> 
> happy (belated) v-day everyone ♥


	3. she's singin baby come home in a melody of tears

**Notes for the Chapter:**

> cass is exceptional, hiro is small and smart, and tadashi is old enough to understand that his entire world was ripped away in one night. this will probably be part one of however many plotbunnies attack me for mini!hamadas and cass learning how to adapt to taking care of impressionable kids that are simultaneously independent and dependent 
> 
> ty for all the lovely feedback you guys keep me going smooches (´ー｀)♥ 
> 
> (chapter title from 'jet pack blues' by fob because tbh most of their songs wreck me lmao)

Hiro’s first real tantrum happens in the middle of a crowded grocery store, surrounded by angry old ladies and frustrated teenagers, two weeks after the accident.

It happens awfully fast: one moment she’s asking Hiro which soup he’d prefer for dinner, and the next moment he’s shouting at the top of his lungs, a broken sound that breaks Cass’s heart four times over. She’s not sure where to go from here; crying children have never been her specialty, always the spoiler to her brother’s kids, and now she’s caught in the midst of a hurricane. She wishes she had a remedy for a confused and lonely heart, a cure for broken families, but she doesn’t—she’s just as lost as Hiro is, wading through a world she doesn’t quite understand.

Cass forgets about the cans and bends down to Hiro’s eyelevel, desperate to calm him down when she says, “Hey, hey, it’s okay, what’s the matter?”

There’s no reply she can make out, just a deep, lung-rattling whine filled with anguish, and Hiro covers his ears with his hands.

She’s vaguely aware of the ladies behind her, stern and aged, a whisper of _this is why young people shouldn’t have children, such a shame_ and _can’t even get control of her own child_ but she pays no mind. It’s not their business, this life of theirs, this tragedy.

“Hiro, Hiro,” she chants, smoothing the hair back from his forehead and urging him to look at her. “Baby, I need you to breathe. Can you do that? Breathe in, breathe out.”

He might be having a panic attack, she notes. It’s the way his eyes won’t stop darting around, the overwhelming sensation of drowning, the air that can’t reach his lungs. She grabs each side of his face and he looks at her between his last scream and the next, looks her dead in the eye, and she whispers, “I love you, okay?”

“I want—I want ‘Dashi,” he manages, hiccups like bumps in his words. Cass nods because she can deal with that, she can totally work with that; as long as Hiro remembers to breathe, she can handle it. “I wanna go home.”

“Okay.” She sets the basket down and ignores the guilt at leaving a mess before holding out her arms, Hiro immediately throwing his own tiny arms around her neck and clinging awkwardly. She picks him up, supporting him as best she can with her purse falling off her shoulder. “Let’s go home.”

They stare at her, judge her—she’s not embarrassed, but she can’t bear the thought of anyone looking at Hiro and thinking _burden_ , thinking _some children are better off in the system_ , because this genius bundle of anxiety and confusion is now _her_ bundle of anxiety and confusion, and she’s trying, she’s trying _so hard_. Cass isn’t a mother. She never wanted children of her own, never wanted the dependence and the heartbreak, but half of her family is gone and she’s the only one left.

Her hands shake when she shoves the key into the ignition, Hiro’s sobbing a constant stream of misery in the backseat, a mess of broken Japanese and his brother’s name.

She’s going to fuck this up. Gods, she’s going to fuck this up.

*

He wants Tadashi, wants his brother home immediately, and she isn’t sure how to explain that Tadashi has to go to school, that it’s been two weeks and the board is going to declare her unfit if she can’t even get them to pursue an education.

It’s only been two weeks. Tadashi can’t sleep without breaking down in her lap, won’t sleep at all unless Hiro is already in bed, and no one has bothered to ask him if he’s haunted by ghosts or if he’s just being swallowed up by the memories.

“Do you want to watch a movie?” she asks eventually. Hiro has curled into a ball on the couch, small and guarded. He looks so terrifyingly unhappy; he’s too smart for his own good, has already surpassed his brother, yet the concept of death is a lesson he never prepared for. All he has are photographs and Tadashi’s grief that wraps around them like a snake. “Anything you want.”

“No,” he mutters, somehow managing to shrink even further. His shirt’s too big, his hair is a nest, and when she catches a glimpse of his face, it’s red and swollen and puffy. “I want Tadashi.”

It’s the first time they’ve been apart since the night she picked them up in the hospital.

It terrifies her to think about.

*

At eighteen, she told her brother that she could never handle children. He had laughed and hugged her tight, said, “You’ll make a great aunt someday.” She loved him and she loved his wife, a close-knit dysfunction that made her want to be a better person.

He promises her, “I’ll support whatever you want, Cass,” a promise that she holds onto until the screeching phone call at three in the morning, the apologies bleeding like open wounds in the waiting room, a fester that leaves her hollow and breathless.

They say, “There was nothing we could do. Instant. They didn’t feel a thing,” as if the idea of a painless death reconciles the utter and terrible sorrow brought upon the living.

A month ago they were planning Tadashi’s ninth birthday. Now she has to plan a funeral.

She’s barely twenty-two.

*

Cass finally manages to get him to nap, tucked tightly into the corner of the couch with the teddy bear Tadashi had given Hiro on his second birthday. His chest rises and falls in a rhythm of disturbed sleep and she catches herself watching him, looking out for signs of nightmares or terrors or whatever it is that haunts small children when they’re unguarded; he’s gripping the bear so tight she’s afraid it might break, but she can’t bring herself to save it. It’s a safety blanket. It’s his lifeline.

It’s the closest thing he has to his brother right now and it’s _killing_ her.

After a half an hour and the reassurance that Hiro is calmed down enough to stay asleep, she busies herself with cleaning up the kitchen, the neglected mess of heartache staining her counter and stove. She’s not used to cooking for more than one at night, not used to having the café closed for days at a time, and the extra food in her fridge is a reminder that she’s out of her league; she needs to make a list of what to buy, what to avoid, what Tadashi won’t eat and what Hiro can’t. She’ll need toys, school supplies, snacks and bedding for Hiro’s bed she’s picking up in a week because Tadashi is getting too big to keep sharing his own bed, is going to acquire a sense of dependence if she can’t separate them now and then, and she has forty-three thousand things to take care of but—

A mug slips out of her hand, crashing to the floor with a resounding _clang_ , and the handle splits from the body and rolls somewhere under the fridge.

If this was her English lit class, she’d recognize the metaphor for what it is, the awful break in her defenses that has her sliding to the floor in defeat.

For the first time in two weeks, she allows herself to grieve.

*

At two-thirty she gently rouses Hiro from his slumber, a slow burn as he rubs his eyes wearily and searches for the familiar people he’ll never see again. She hooks her hands under his arms and cradles him against her shoulder, carrying him downstairs so she can get her shoes on and slip his feet into his sneakers.

“It’s time to pick up Tadashi,” she says quietly, adjusting him and breathing a sigh of relief when Hiro clings to her neck. He trusts her. It makes her so, so sad.

“Home,” he tries to explain, tugging at her hair. Cass laughs, kisses his forehead. “Home?”

“That’s right, baby,” she nods, her eyes stinging with something like hesitant joy and anxious hope. “We’re bringing him home.”

*

Tadashi is sitting on the steps in front of the school, his backpack forgotten beside him the moment he sees Cass pull up, and she unbuckles her own seatbelt before stepping out of the car to do the same for Hiro. If this becomes their routine, the happy screeches when Tadashi runs forward to wrap his arms around his brother’s tiny frame and the rapid back-and-forth Japanese, then she’ll do this every day. Tadashi’s still pale, eyes bruised and exhausted, but Hiro’s attempting to climb into his arms and Tadashi _laughs_. She wants to bottle it up, wants the reminder that her nephews can remember how to breathe, the temporary elation that maybe, maybe she can do this, maybe she can nurture and keep them healthy at the very least.

 _Everything always works out_ , he had taught her, five years old and curious. _I promise, Cass._

She’ll pass it on. Tadashi hugs her around the waist and she runs her fingers through his hair, Hiro a weight on his brother’s back.

If nothing else, they have each other.

*

She tells Tadashi, “They want to put him in advanced classes, have him skip a few grades…” and he’s torn between pride and guilty jealousy, a confused parting of his lips as his eyes finally, _finally_ come to life.

“That’s great, Aunt Cass, isn’t it?”

“It is,” she agrees with a nod, tucking his hair behind his ear. He’ll need a haircut soon. “He’s going to be confused for a while.”

Tadashi shakes his head, folds his notebook filled with hasty equations closed, and says, “He’s not confused, I think. Just lonely.”

She’s not sure what to say to that—how can he be so lonely, how can she not _see_ it, how can she fix it? Cass can’t decipher Hiro the same way his brother can, though heaven knows she’s trying. Tadashi seems to take pity on her, a sad smile curving his lips like a saving grace, and she hates how heavy this is for all of them.

This life of theirs.

This almost tragedy.

“I’ll watch out for him,” he assures firmly, jaw set with determination. She hasn’t seen him this lively in what feels like an eternity of burning galaxies and broken stars, and Cass scoops him up and holds him close in a desperate attempt to piece themselves back together. Hiro is asleep on the sofa, a documentary on starfish echoing as background noise from the television, and Tadashi clings to the cotton of her shirt and whispers, “I promise.”


	4. lost time tastes an awful lot like disappointment

**Notes for the Chapter:**

> i actually had half of this sitting in my drafts for like two weeks and finally decided to finish it up
> 
> warnings for sickly gross stuff, vomit, etc etc. hopefully it's not too graphic hhhhh 
> 
> i love tadashi taking care of hiro i am a sucker for it and i am also a sucker for hiro taking care of tadashi so who knows maybe tadashi ends up contracting what hiro has............
> 
> tysm for the feedback guys!! ♥

“You’re going to school, end of story.”

“But—”

“I know you’re worried, honey, but we’ll be fine.”

“He’s _sick_ , Aunt Cass. _Sick_. He wouldn’t even let…”

From his perch on the stairs, Hiro can hear the entire conversation with practiced ease; he keeps a tally in his journal of how many times he gets away with eavesdropping, everything from the strange argument about whether or not soy milk is a better alternative (if it’s chocolate, Hiro doesn’t really care either way), to the nastier near-explosive fights about financial stability and whether the café is in danger or just sort of… not (he tries not to think about _that_ one too much). He’s turned it into an art form, the way he sits on the third step down, out of immediate sight but in perfect hearing range. Usually he even shoves a plastic bag full of some sort of candy in the pocket of his khaki shorts, but this morning had involved being awake for approximately three-point-two seconds before having to make a mad dash to the bathroom and emptying last night’s breakfast, lunch, _and_ dinner.

He’s not proud of that one. Hiro’s pretty sure he almost gave Tadashi a heart attack with the way he practically threw himself out of their room, coming into contact with the edge of two walls and the corner railing. His hip is already starting to bruise.

“You know how he gets,” Tadashi begins, and Hiro perks up, tries to catch the reason for the sudden halt. When all that follows is silence, he sighs quietly and goes back to fiddling with a loose thread at the bottom of his t-shirt; they’ll start talking eventually.

Except they don’t. A set of footsteps head his way and the irrational panic sets in, urging him up and off the stairs, the second mad dash of the day as he barely makes it under his covers before someone comes padding in.

Tadashi doesn’t sound disappointed, just tired, when he says, “I know you were listening.”

“Nope,” he lies. Deny, and maybe his brother won’t give him the _look_. “Too sick.”

Hiro punctuates it with a cough. Tadashi, unsurprisingly, doesn’t buy it.

“C’mon,” he says, nudging at Hiro’s blanketed form with his hand and a small smile. “I need to take your temperature anyway.”

“Thought you had school,” he mumbles, curling deeper into his manmade fort; it isn’t a big deal that he’s sick, he thinks, because being sick means staying home with Aunt Cass’s homemade miso soup, and staying home means no additional threats of bodily harm from the seniors in his chemistry, biology, and world history classes. It means working on his robots in peace, a win-win situation as far as he’s concerned.

“I do,” Tadashi agrees, taking a seat on the edge of Hiro’s bed. Subconsciously, Hiro shifts closer, attempting to make room but mostly seeking out the warmth. “But as I told Aunt Cass, you’re my priority.”

“Education is important,” Hiro tries. It earns him a snort and a light slap on his leg before Tadashi forgoes the pleasantries and rips the blanket off him. “Hey, _hey_ , it’s cold out here!”

“Mhm.” He places his cold, treacherous hand on Hiro’s forehead, immediately frowning. “Hiro, you’re burning up. Can you cooperate for thirty seconds? Please?”

And this is why Hiro loses forty-five percent of the bets they place, because Tadashi has mastered looking like a kicked puppy in the heat of the moment and right now, Hiro doesn’t have the heart to say _no, Tadashi, you may not stick your metal contraption in my mouth for any length of time_. He’s back somewhere around zero and Tadashi is probably in the high teens, though Hiro has no qualms about calling him out as a cheat. They have _rules_.  

“…Fine,” he mutters, crossing his arms over his chest to make his point. Tadashi has the decency not to laugh at his brother’s wounded pride, opting for grabbing the thermometer from his side of the room and coming back to stick it under Hiro’s tongue. It’s cool, tastes faintly of blood, and Hiro despises it with every fiber of his being, but he can’t deny that he doesn’t feel a pang of worry when Tadashi’s brow furrows with concern.

“100.2,” he says, shaking the thermometer for something to do with his hands. Hiro bites his lip, scratches the back of his neck.

“I don’t feel that sick,” he admits, shrugging. “I mean, if I eat something it’s probably gonna come right back up, but I’m fine. Really.”

“You’re not fine,” Tadashi argues, yanking the blanket back up to drag it over Hiro. “And I don’t want to hear any arguments. I’ll have Aunt Cass bring up some Gatorade and you’re gonna spend the day in bed, okay?”

“But—“

“Nope.” He gently pushes Hiro’s shoulder until there’s no choice except to comply, though the angry twist to Hiro’s mouth is probably enough of a giveaway. “If you need anything, call for Aunt Cass. I’ll be home around one.”

The rational part of Hiro knows he should listen and try to sleep, a flu-ache settling in his bones and muscles that makes it difficult to concentrate, but a free day is still a free day and he’s _so close_ to finishing his latest bot, his ticket to freedom. He says, “I’ll try,” to placate his brother, and then waits for the telltale sign that Tadashi has left, revved up his moped, and zipped away.

His alarm clock reads 9:34.

This could work.

-

Hiro plays the sick card with practiced ease when Aunt Cass treks upstairs twenty minutes later, a bottle of red Gatorade in one hand and a plate of soda crackers in the other. He peeks out of his nest, tries to look as pathetic as possible, and she sets both down on his nightstand with a frown.

“Oh, honey,” she says, brushing his fringe away from his forehead. “You must have picked something up at school.”

He doesn’t think about how close Bobby had come to sneezing in his face and says, “M’fine, Aunt Cass,” which has the intended reaction of another hair pet and a promise of letting him sleep for as long as he wants.

“If you’re feeling better later, I’ll make some soup,” she murmurs, tucking him back in. Hiro catches the worry-stress lines like scars on her forehead, the shadows under her eyes and just for a moment, there’s a shock of guilt through his stomach, a reminder that he’s figuratively in the dark about everything. “Now sleep, or your brother will lecture _both_ of us.”

He gives an indecipherable groan and listens to her footsteps echo quietly in the hallway; counting to a hundred in his head, he reaches over for the bottle, downs a quarter of it in one go, and grimaces at the burning in his throat. No other signs or sounds alert him to his aunt’s constant need to reassure herself that her nephew is fine, so he takes the opportunity to toss his blankets away and start digging through his drawers for a pair of pants. There’s a three second margin where he can’t see anything and his room threatens to cave in, but it’s gone and he decides that no, it’s not an issue, he’ll deal with it later because the next bot fight is tomorrow night and he’s _running out of time_.

“Okay,” he mutters, hands shaking slightly when he goes to tie the drawstring on his pajama pants. He throws on one of the hand-me-down tees that Tadashi had practically drowned him in, sighing in relief when it doesn’t swallow him whole and deliver him to another dimension of oversized shirts. “Okay, I got this.”

The first obstacle: Mochi.

The poor cat looks incredibly comfortable in front of the stairs and while Hiro hates to interrupt, casualties are inevitable; he gently scoops Mochi up, repositions him beside the railing, and breathes a sigh of relief when Mochi purrs and licks his hand before returning to his snooze.

Second obstacle: Aunt Cass.

Hiro, theoretically, can take the back door in silence and not alert his aunt to his whereabouts, but there’s always the possibility that Cass is bustling in the kitchen, which puts a damper on his plans to scoot out as quickly as possible. He perches on his step for thirty seconds but hears nothing except the washed-out noise of the café below. He can vaguely hear his aunt’s voice, no doubt talking with one of her regular customers; if he has any chance, it’s now.

It’s seven steps down the stairs (he’s never been so grateful for socks), eight to the back door (he grabs two shoes, though one feels just a tad too big), and six to the garage.

-

If his calculations are correct—and they usually are—he has an hour and a half until Cass’s break and subsequent check-up. The last time Hiro remembers being sick was when he was five and Tadashi hadn’t known, leaving his aunt to deal with Hiro’s temper and desperate need to bounce around and _do_ things despite the ache in his stomach. It had been a nightmare, but Hiro had kept a timesheet of when he was interrupted to have his temperate taken, fluids forced upon him, or just the general hover of a very worried, inexperienced aunt, resulting in a very intricate Sick Schedule he keeps under his bed in case of emergencies.

Hiro loves her, he does, but she doesn’t understand that Hiro _can’t_ be sick because he has twelve projects to finish, only one of which is actually school related, and ‘illness’ is not in his vocabulary.

Clapping his hands together and glancing to his computer near the back of the garage, he gets to work.

-

“Too big,” he mumbles, shrinking the object on screen with his tongue between his teeth. His hands won’t steady and his arms are difficult to move, a lesson in water dynamics, but he continues. “If I change the ratio… but that leaves the whole thing unbalanced…”

An alarm beeps shrilly somewhere to his side and he jumps, groaning at the roiling of his stomach it induces. The time at the corner of his screen reads 10:57 and Hiro refuses to panic when he closes the schematics and races towards the door, his palms hitting the wall to stop his trajectory and causing him to hiss through his teeth as he toes off his shoes. He goes backwards in his steps, thinks, _there’s still no sound from the kitchen so she must be in the café, it’s fine_ , which leads him to the stairs and Mochi’s guardianship of the entire hallway. He doesn’t bother with moving him, doesn’t have the energy, just steps over him and hightails it into his bed.

Four crackers find their way into his stomach, followed swiftly by more of the Gatorade, and thirty-three seconds later Cass is knocking on his door.

-

“I need to take your temperature, Hiro.”

“Tadashi already _did_ that.”

“Think of it as a lollipop—“

“That’s disgusting!”

A frustrated sigh and a tug at his blankets, Hiro shoos away his aunt’s hands and delves further into his fort. Tadashi had called it his safety space, a kneejerk reaction to unpleasant things that Hiro clings to.

“If your fever has gone up, I need to know,” she says softly, and it catches Hiro’s skewered attention. He’s not even sure _why_ he’s fighting her on this, only knows that the stupid thermometer always tastes awful and leaves his mouth feeling sore and strange. “Please, Hiro.”

He doesn’t say yes, but he lets her pull the blanket away enough to see his face and gently stick the thermometer under his tongue. It’s an awkward silence that follows, though Hiro has a hard time focusing on anything anyway, hyperaware of the tension in his shoulders and neck, the sweat beading on his forehead and the palms of his hands. When it finally beeps, he swallows thickly and nearly vomits from the sensation.

“101.1,” she murmurs, absently carding her fingers through Hiro’s hair. “If it goes up any more I might—“

“No hospitals,” he says weakly, hating the sound of his own voice. It makes thinking difficult and if this keeps up, he’s not even going to be able to _move_.

“No hospitals _yet_ ,” she corrects, scooting off the bed. “If it doesn’t break by tonight, I’ll call our doctor.”

“But he smells like pineapples,” Hiro groans, burying his face in his pillow in an attempt to remind his lungs how to breathe. “And air fresheners. Why does he smell like air fresheners?”

“I wouldn’t say air fresheners,” she teases, fixing his blanket and patting him on the leg. “Though there _is_ that undercurrent of pine…”

Hiro gives a half-snort that sounds terrible and sickly, and not for the first time, he curses his suddenly awful immune system.

Cass says, “I’ll let you sleep, okay? Just relax,” and he listens to her patter out of the room with an increasing awareness that he’s truly, royally fucked.

*

He’s just going to rest his eyes for a few minutes, that’s all.

*

The next time he wakes, his alarm clock flashes 12:26 at him and he breathes a sigh through his nose; his entire body feels bruised and heavy, his hands are shaking, and there’s the distinct sensation of vertigo that lingers every time he so much as exhales.

Last time it was Tadashi who was sick, a terrible head-cold-flu combination that left him unable to leave his bed without fear of tripping or losing the contents of his stomach, and Hiro remembers wetting cold cloths and helping him drink to avoid dehydration. Between the two of them, Tadashi’s immune system is worse, but it’s not a common thing for either of them to actually succumb to a virus—and when it _does_ happen, they’re usually not alone.

But Hiro _is_ alone, and he’s not five and angry and desperate to build, he’s just twelve and sort of lonely, sort of nauseous.

“Rule sixty-seven,” he murmurs into the quiet, rubbing bitterly at his eyes. He feels gross. “If one of us is too sick to get out of bed, the other has to stand guard so he doesn’t do something stupid.”

He blames it on the delirium, this horrible fever-dream state, and falls asleep to the sound of his ragged breathing.

*

“Goes here…”

There’s a sharp pain in his thumb, enough to wake him up, and Hiro’s not sure whether to be terrified or impressed that he’s managed to pick apart one of the failed thrusters while half asleep, a scattered mess of screws and forgotten circuitry.

1:21.

There’s a drop of blood welling where the screwdriver managed to catch his skin, and he sucks on it petulantly, rolling himself over to his bed with every intention of climbing back into it.

It backfires, of course, and all he can do is tug the blanket off his mattress and curl into it, his chair squeaking in protest.

*

“Only you,” he hears distantly, a comfort in the midst of the heat licking at his skin. “— _bed_ , is that so hard?”

Hiro thinks he might have laughed, might have weakly protested at being moved so suddenly, but there’s a cold hand on his forehead and he doesn’t care.

*

He dreams, but he can never recall them when he’s awake long enough to realize that he’s not alone.

*

“The ending was pretty clever.”

“Too predictable.”

“Everything is too predictable for you boys.”

Hiro groans, followed by one of the worst coughing fits he can recall, and is promptly rewarded with an ache in his throat and two pairs of worried hands fidgeting over his bed.

“M’fine, _fine_ ,” he grits out, staring at the abandoned laptop on Tadashi’s bed. There’s no real light filtering in through the blinds and all the lamps are turned off, so he can only surmise that it’s after dark and he has, unfortunately, slept the day away. At least he’s lucid; a small victory.

“It’s ten after ten,” Tadashi assures him, offering him a bottle of warm water. Hiro’s hands are too unsteady, too unsure, and his brother takes pity on him. It’s a small blessing that the water doesn’t immediately upset his stomach.

“No more bravado,” Cass says gently. “How are you really feeling?”

Hiro thinks for a moment, finds that the day is mostly a blur, his thumb is sore, there’s a dull throbbing at the base of his skull spreading to his temples, and he can’t keep his gaze steady _at all_. Tadashi is a beacon of warmth at his side and Cass is easing some Gatorade past his lips in his moment of distraction, but overall: it could be worse.

He settles with, “Nngh,” which Tadashi understands because they’ve been in stranger situations than this, and Cass caps the bottle and disappears into the bathroom for a few seconds before returning with a damp facecloth.

“Your fever’s gone down,” she explains, placing the cool cloth over his forehead and gently helping him lay back down. Tadashi treads past the collection of stray experiments on their shared floor and grabs his laptop. “Do you think you can handle some soup?”

His stomach is the least of his worries.

“I think so.”

“Great.” She cards her fingers through his hair one last time, sharing a look with Tadashi that Hiro’s too tired to decipher, and then she’s heading downstairs and he really, really has to pee.

“I have to pee,” he states, kicking the blankets away and attempting to stand up. The cloth slips off his face and Tadashi steadies him with a hand on his shoulder, guiding him to the bathroom, only looking away to let Hiro do his business. He leads Hiro back to bed once he’s done and grabs another damp cloth; it’s a silent endeavor and Hiro’s pretty sure his brother is gearing up for a lecture.

“I’m invoking rule twenty-eight,” Hiro mutters pre-emptively, which earns him a snort and a flick to his nose. “Seriously!”

“Okay, okay,” Tadashi acquiesces with a small smile, tucking Hiro under the sheets before climbing in beside him, his computer in his hands. “No need to invoke any rules, kiddo. I don’t think I have the energy to lecture you anyway.”

Hiro nods to himself, chews on the inside of his cheek for a few seconds; Tadashi’s fiddling with his files, probably digging up something to watch, and Hiro rests his head on his brother’s shoulder with a sigh.

“You’re really out of it, aren’t you?” Tadashi asks, adjusting them both so Hiro’s less likely to pull something in his neck and the facecloth can’t slip over his eyes.

“Not out of it,” Hiro murmurs around a yawn. He’s completely in control of his own body at the moment, no fever-dreams lingering at the edges of his subconscious; he’s just tired, a bone-deep ache that can’t be slept away. “Learn anything cool at nerd school?”

“I learned that my friends can’t be trusted around sharp objects,” he teases, reaching over to lift up Hiro’s left hand. There’s a yellow band-aid wrapped around his thumb. “And neither can my little brother, apparently.”

Hiro laughs, only a bit deliriously, at the realization that he hadn’t dreamt it. “I _did_ take it apart, holy crap—“

“You got blood on your pillow, knucklehead—“

“I wasn’t even awake!”

Tadashi’s frowning at him like the world is a disastrous danger-zone and it’s Hiro’s fault, so Hiro sticks out his lower lip and touches the file marked _spongebob??_ in an effort to redirect his brother’s attention _._ Tadashi, unfazed, pauses the video before it can play and says, “What do you mean you weren’t awake?”

How to explain sleep-deconstruction without sounding crazy: not possible.

“It’s nothing,” he tries, waving his hands uselessly to punctuate this.

“Hiro.”

“I was sort of sleeping at the same time?”

“Sleepwalking.” Tadashi raises an eyebrow and Hiro shakes his head. “I know you snuck out to the garage earlier, but _please_ tell me that you were awake.”

“What—“ Hiro groans, banging his head against the soft cotton of Tadashi’s sweater; he makes a mental note to never, ever get sick again. Ever. “I was… yes, I was definitely awake for that, because it was after you left.”

“I’m glad I can trust you to sleep when told,” Tadashi deadpans, to which Hiro scoffs and says, “I was _bored_ ,” and Cass chooses that moment to walk in with a steaming bowl of what Hiro guesses is chicken noodle soup.

“You guys will have all the time in the world to argue,” she begins, handing the bowl to Hiro’s outstretched hands, “ _after_ Hiro’s feeling better.”

The very childish, very immature part of him has the urge to stick his tongue out at Tadashi, but he sincerely doubts it’ll help his case. Regardless, Cass is kissing his cheek and brushing his hair away from his face and his chest feels a little less tight, a little less lonely, a knot he wasn’t even aware of.

“Don’t be up too late,” she says with a smile and a pointed look in Tadashi’s direction, who merely shrugs it off and pulls her in for an awkward hug without jostling Hiro in the process. “ _Both_ of you need sleep.”

“Yes, Aunt Cass,” they chorus and she bids them a quick goodnight.

The warmth of his bowl is rivaled only by his brother, and Hiro gives up on excuses and thoughts about robot schematics that are mostly done anyway, settles for sipping the broth and curling in closer to his brother. Tadashi laughs—kind and patient and exhausted, a rattle deep in his chest—and drapes an arm over Hiro’s shoulders.

“Spongebob, huh?” he asks, hitting enter and positioning the laptop so it’s easier access for both of them. “Haven’t watched this in ages.”

“Something different,” Hiro mumbles, toying with his spoon and debating whether or not it’s worth it to eat the noodles. “Plus, hey, a talking sponge. That’s true history right there.”

And it’s nice, this comfort between them, something Hiro didn’t know he missed until he woke up to Tadashi stroking his hair sometime in the mid-afternoon; he doesn’t remember much, but maybe it doesn’t matter.

“See if you can keep that down,” Tadashi says, rubbing his arm soothingly and relaxing into the headboard.

Naturally, he doesn’t.

*

As it turns out, the toilet ends up being his best friend through the late hours of the night, a constant emptying of his stomach that his him dry heaving and clutching at his hair to steady himself. Tadashi’s up for most of it, his hand a comforting pressure between Hiro’s shoulder blades, and he shoos Cass away at some point to get some sleep; he doesn’t have class until noon anyway.

“This is so gross,” Hiro accomplishes between coughs, his skin clammy and warm and uncomfortable. If he could crawl out of his own body, he would. Tadashi places a paper cup with a bit of water to his lips and Hiro swishes it around, pleading with his abused stomach to hold out until after he spits it into sink. “ _So_ gross.”

“Here.” Tadashi is gentle as he wipes at the corners of Hiro’s mouth, the tissue coming away with a bit of blood. Hiro spares a moment to panic before his brother shushes him and throws it away. “It’s from your lips. You’d know if you were vomiting blood.”

It fails at making him feel better but hey, small victories.

*

“Think you can stand?”

Hiro’s knees feel glued to the linoleum floor at this point, terribly sore, and he’s pretty sure his bones crack when Tadashi helps him stand with an arm around his waist and a hand on his hip. He hasn’t been this dependent on anyone since—well, since the last time he was sick, probably, and he’s not sure how long his patience can last, this constant need to wrap himself around the toilet every twenty minutes. After an hour, he doubts his stomach can take much more.

“I’ve got a bucket beside your bed,” Tadashi murmurs, easing him back into their bedroom, and Hiro _knows_ Tadashi has a test tomorrow and it’s not fair that it’s after two in the morning and neither of them have actually slept.

“I wanna change,” Hiro says feebly, getting his head caught in his shirt when he tries to peel it off. Tadashi’s clearly trying not to laugh and Hiro feels absolutely _gross_ , would much prefer to drown in the bathtub, but Tadashi helps him into a clean t-shirt and pajama shorts because Hiro can barely stand on his own, let alone get dressed.

He can’t even be embarrassed.

“Scale of one to ten?” Tadashi asks, sliding the palm of his hand under Hiro’s bangs and checking for signs of fever; it turns out to be more comforting than anything. Hiro closes his eyes, breathes in, and is extremely proud that he doesn’t burst into tears at the sharp pain in his stomach.

“A six, maybe,” he grunts, pointing in the vague direction of his bed. “It’ll be a zero when I’m asleep. Why couldn’t this just—,“ he makes an aborted gesture with his hand, “—go away. The fever went away. M’not hallucinating anymore.”

There’s a beat of silence and Hiro wonders if he said too much, but then Tadashi says, “You never do things normally, knucklehead,” like that explains why his body is torn between burning itself up and rejecting any outside sustenance. Maybe it does; maybe Hiro has always been doomed to surrender completely to some invisible illness.

“C’mon,” Tadashi urges, an attempt to lead Hiro to his bed backfiring when Tadashi’s ends up being closer. Hiro doesn’t hesitate, just throws himself onto Tadashi’s bed with a grumbled curse, curling into himself on top of the blankets.

If Tadashi has a problem with it, Hiro doesn’t stay awake long enough to hear it.

*

“Bucket, _bucket_.”

“Breathe, Hiro,” and he tries, he honestly tries, but the second the bucket is in his hands, he’s throwing up acid, a bitter burn at the back of his throat that makes his eyes water. Tadashi’s hand never leaves his back, his head. “You’re gonna be fine.”

*

He nods off a few times, the curve of his spine settled comfortably against his brother’s chest, the bucket a saving grace in his lap.

*

Finally, _finally_ his stomach calms at four o’clock in the morning when the sun is still set and the breeze billowing through the crack in their window is cool and welcome on his fevered skin. His nose is stuffed and his throat feels sandpapered and awful, but he can climb under Tadashi’s blankets without the world caving in and that’s progress, that’s _great_. Tadashi putters around the room for a bit, offering Hiro the remainder of the Gatorade that Hiro’s more than happy to drink, and it’s not long until he’s drifting off without the fear of choking. Tadashi slides in next to him, exhausted and worn, and Hiro pokes him in the ribs to get him to relax.

“That’s counterproductive,” Tadahis mutters tiredly, already beginning to doze off. Hiro can’t blame him. “Also, bro, your toes are _freezing_.”

“Not my fault,” he croaks, biting back a yawn.

“It’s definitely your fault.”

Hiro snuffles, too drained to argue, and burrows deeper into the blankets until he’s completely surrounded by warmth. Tadashi doesn’t question it, either devoid of energy or care or both, and merely tugs the blanket far enough down so Hiro can’t suffocate.  

“Sleep now,” Tadashi slurs, and Hiro laughs, grimacing when it irritates his throat.

He falls asleep to his brother snoring in his ear.

*

Cass finds them like that in the morning, tangled together in the chaos of sheets and sleeping so deep she’s half afraid they’ll never wake, but—

“My boys,” she smiles, takes their dishes, and leaves two bottles of warm water and a plate of lightly buttered toast. She’s not sure what she’d do without Tadashi, and she can’t imagine her world without Hiro’s boundless energy; she snaps a photo on her phone and leaves the two in peace.

It never hurts to have blackmail, either.  

**Author's Note:**

> [♥](http://arbhorwitch.tumblr.com)


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